Young's Modulus

The slope of the line in a stress-strain diagram in the elastic region. Before the yield stress.

Also called the modulus of elasticity or elastic modulus.

If a wire is stretched, then so long as it is not stretched too far, it will behave a bit like a spring. (See: Hooke's Law)

The Young's Modulus of a material is the stress divided by the strain

Stress = Force over area
Strain = Extension over original length

NB: Stress causes strain.

Modulus of elasticity = stress / strain

The modulus has the same units as stress. A large modulus means that a large stress is requird to produce a given strain - the object is rigid

Accordingly, Y = ( F/A ) / ( Δ/L₀ ) = FL₀ / AΔL

Its SI unit is Pa. Unlike the constant k in Hooke's Law, the value Y depends only on the material of the wire or rod], and not on its dimensions or configuration. Consequenty, Young's modulus is an important basic measure of the mechanical behavior of materials.